It shouldn't be going anywhere if it's CCed, and neither should the other mobs now. All CC will now work like Sap does: you can use it before pulling without having all the mobs charge you. So instead of having to Polymorph after the tank pulls or have the tank pick up aggro when the mage Polymorphs as the pull, you can use all that CC before the pull and then have the tank pull like normal. So everything like Polymorph, Hex, Bind Elemental, etc., will be usable without pulling.

I haven't seen this questioned asked before, but does anyone know if a Druid's Roots will pull the group since it actually does damage?

Roots damage is being removed, to fall inline with the CC changes. So no, Roots will not pull.

Not so sure that they'll work JUST like sap does; sap eliminates facepulling, too, and from what I recall of the description of the changes, you'll still be able to facepull non-sapped CC'd mobs. They'll be impotent, since they're CC'd, but you'll still end up on their aggro table, and the aggro tables of any friends the CC'd mob is linked to.

On the other hand, I've not tested it on the PTR, nor read any first-hand experiences with the new CC, so maybe it is exactly like sap. Except for the ability to apply it in combat.

Sadly repentance will still pull. More exactly you have to be so close to the mob that you'll facepull. I don't see the point of it only having a 20 yard range but I'm not a game designer.